Next Generation Digital Vehicle Platform Provides Foundation for Future Technology . . . . . . . . . . . . . .2

Diesel Fuel Additives . . . . . . . . . . . .4

Whistle Sound from the Engine . . .5

Intermittent Shift to Park Message . . . . . . . . . . . . . . . . .11

Transmission Control Module Connector . . . . . . . . . . . . . . . . . . . .13

Getting Ready for Techline Connect

New EL-52545 TPMS and RF Tool Makes TPMS Sensor Relearn Easy

see page 8see page 6

CUSTOMER CARE AND AFTERSALES

Next Generation Digital Vehicle Platform

Provides Foundation for Future Technology

October 2019, Volume 21, No. 19

October 2019 – Page 2

CONTINUED ON PAGE 3

As the technology in new vehicles continues to evolve and

expand, more electrical bandwidth and connectivity has become

necessary to ensure all the data-driven features can operate

efficiently together within the overall vehicle network. The Next

Generation Digital Vehicle Platform, GM’s all-new electronic plat-

form, will be used to help power the next generation of GM mod-

els and systems, including electric vehicles, active safety systems,

infotainment systems, and a variety of connectivity features. The

new platform will go into production later this year with the debuts

of the new 2020 Chevrolet Corvette and Cadillac CT5 and CT4.

The Next Generation Digital Vehicle Platform powers a new

electronic system that is capable of managing up to 4.5 terabytes

of data processing power per hour, which is a fivefold increase

in capability over the current Global A electrical architecture. The

new architecture provides more rapid communications within the

vehicle itself as well as to outside sources with Ethernet connec-

tions of 100Mbs, 1Gpbs and 10Gbps.

The system features the Controller Area Network with Flexible

Data-Rate (CAN FD) protocol, which supports improved data com-

munication and faster programming by transmitting and receiving

data at a higher maximum bit rate. A faster bit-rate allows more

data to fit into a single message, reducing the need for more

networks (and additional wiring) in a vehicle, which also reduces

weight and increases performance.

CAN COMMUNICATIONThe Next Generation Digital Vehicle Platform can incorporate up

to nine high-speed CAN buses. Low-speed GMLAN and MOST are

not used.

Programming and scan tool data information is provided using

CAN buses 6 and 7, which only run between the DLC and the

Serial Data Gateway Module, and are used by GDS 2 to provide

system data from the other CAN networks. This design isolates

the remaining buses to secure those networks and provide en-

hanced intrusion detection incorporated at

the architectural level.

The powertrain CAN bus communicates

over a dedicated circuit but the other CAN

buses use a wake-up message from the

Serial Data Gateway Module, which can

be tailored to wake up individual modules

when needed. The Serial Data Gateway

Module is updated first during program-

ming and then any other modules are

programmed through the Serial Data Gate-

way Module.

TIP: Programming is now done with all

doors closed and the ignition off. With

this new process, the Serial Data Gateway

Module can wake up a specific module for

programming with no other information on the bus, which also

promotes faster programming.

In addition, there are several Diagnostic Trouble Codes (DTC) that

have changed from the previous Global Architecture (Global A) to

the new Next Generation Digital Vehicle Platform.

GDS2 SUPPORTThe GDS2 Core 21.1.07400 software update added Next

Generation Digital Vehicle Platform capability.

For communication diagnostics, the Serial Data Gateway Module

will periodically poll for module communication across all sub-

networks. When a non-communication event is detected, the

information is recorded and presented in a table under Vehicle

Next Generation Digital Vehicle Platform Provides Foundation for Future Technology

October 2019 – Page 3

Diagnostics > Vehicle Communication Diagnostics > Network

Communication Event Results.

The event results include up to 50 records (up to 9 records per

CAN1 or CAN2 and up to 8 records per CAN3, CAN4, CAN5,

or CAN8). Select the CAN Bus Records tab to view the recorded

data. It shows the CAN bus that encountered an event and the

number of times the fault occurred (up to a maximum of 255).

In addition, the timestamps list the time of the first failure — the

larger the number, the more recent the event — and the last fail-

ure, which is displayed when the event is no longer present. The

Delta column shows the difference between current time and the

first failure, with a smaller number indicating a more recent event.

Under the record data, defined control modules are listed by

name while undefined modules will display their diagnostic ID.

Communication status will be listed as Communication Detected

or No Communication Detected. Additional status information

will be added in future model years.

The “Refresh” button at the bottom of the table can be used to

request new data on demand. When events are no longer occur-

ring, the event records can be cleared by selecting the “Clear Bus

Records” button.

Under the Modules Supported on Vehicle tab, the control mod-

ules for the vehicle are identified along with the CAN bus number

connected to each module. Modules connected to more than one

bus will be listed in multiple rows.

The network communication status of the control modules on

each bus also can be viewed by selecting Vehicle Diagnostics >

Vehicle Communication Diagnostics > Network Communication

Status. When checking status, a request is sent to all modules on

a targeted sub-network. Select the Refresh button at the top of

the table to run the status procedure additional times.

The GDS2 software update is available by selecting the GDS2

icon in TIS2Web. For assistance, contact the Techline Customer

Support Center (TCSC) at 1-800-828-6860 (English) or

1-800-503-3222 (French).

Thanks to Chris Henley

First Timestamp Failure is the largest number & Delta is the smallest number = Most recent event Record

CAN Bus Number

Network Communication Status for each bus

Network Communication Event Results

CONTINUED ON PAGE 5

October 2019 – Page 4

As colder winter weather rolls in, GM recommends using

TOP TIER Detergent Diesel fuel in 2014-2020 GM mod-

els equipped with a diesel engine in order to maintain

optimal engine performance. TOP TIER fuel can help

diminish injector deposits while offering enhanced

lubricity and fuel stability — key requirements for mod-

ern diesel engines.

If TOP TIER Detergent Diesel fuel is not available locally, GM

recommends the use of ACDelco Diesel Fuel Conditioner. It

is a multifunctional additive that helps clean engine deposits,

improves lubricity and cold temperature fuel flow, reduces fuel

filter plugging, enhances corrosion protection and fuel stability,

and boosts cetane. And if low-quality fuel has already been used,

GM recommends adding ACDelco Fuel System Treatment Plus –

Diesel to help clean engine deposits.

TIP: Only use Ultra-Low Sulfur Diesel Fuel (ULSD) from pumps

with the ULSD label.

If a vehicle is properly maintained but has fuel contamination

issues, consider obtaining fuel from a different source. Purchas-

ing fuel from a high volume fuel retailer increases the chance

that the fuel is fresh and of good quality.

COMMON DIESEL FUEL CONCERNSFuel Waxing/Icing – A winter fuel additive may be desired to

prevent fuel waxing or icing during extreme cold snaps.

Fuel Cleanliness – Water in the vehicle’s fuel system can lead

to corrosion, increased metal wear, ice during cold weather,

plugged filters or screens, increased degradation of fuel, partial

hydrolysis of biodiesel (FAME) in diesel/FAME blends and micro-

biological growth. Water is also a good solvent for inorganic

salts and can contain dissolved acids or other contaminants that

can harm the engine. Free water in storage or vehicle tanks can

accumulate salts and polar compounds over time and severely

impact fuel injection and engine operation. Elimination of water

and microbial growth, along with the use of corrosion inhibitor

additives, will significantly reduce the amount of corrosion and

particulate generation throughout the distribution system. Diesel

fuel contaminated with abrasive inorganic particles can cause

abrasive wear of the fuel system and the piston rings. Fuel injec-

tors and fuel injection pumps are particularly susceptible to wear

because the high liquid pressures they generate require extremely

close tolerances between parts moving relative to one another. If

cleanliness concerns with diesel fuel

are suspected, a sample from the

fuel dispenser or fuel from the tank

(1 quart or a liter) should be visually

observed in a transparent container.

Good fuel samples should appear to

be bright and clear.

Fungi Growth – Bacteria and fungi

growth can occur in diesel fuel when

there is water present, especially

during warmer weather. The best

prevention against bacteria and

fungi growth is to use clean fuel that

is free of water. There are diesel fuel

Diesel Fuel Additives

October 2019 – Page 5

biocides available that are designed to kill bacterial growth in the

fuel system. However, the dead bacteria can still cause blockages

throughout the fuel system. If bacterial growth is found in the

fuel system, the proper method of removal is to flush the fuel sys-

tem using the appropriate Service Information procedures, replace

the fuel filter element and refill the tank with clean diesel fuel.

Low Cetane Number – The cetane number is one indicator of a

diesel fuel's ability to ignite. There are many indicators of overall

fuel quality, such as cleanliness, specific gravity, volatility, viscosity,

detergency, corrosion inhibiting abilities, and lubricity. Increasing

the cetane number alone is not a fix for poor quality fuel and will

not increase engine performance.

Poor Lubricity – The 2.0L diesel engine and the 6.6L Duramax

diesel engines are designed to operate on today's low sulfur fuel

without the use of additives. A fuel additive designed to increase

lubricity is not a fix for poor quality or contaminated fuel.

Fuel Stability – Fuel Stability and degradation may be a concern

for diesel fuels, especially for diesel fuel containing biodiesel. The

use of aftermarket stability additives to improve the quality of a

degraded fuel is not a fix and use of such aftermarket stability

additives is discouraged due to concerns of proper mixing and

fuel compatibility.

TIP: Any fuel additives used must not contain any metal-based

additives, alcohol or other water emulsifiers that may compromise

the water removal effectiveness of the fuel filtering system.

For more information about TOP TIER Detergent Diesel fuel as

well as a list of TOP TIER diesel fuel retailers, visit toptiergas.com.

Thanks to Larry Yaw and Shailesh Lopes

Whistle Sound from the EngineThere may be a whistle or squeak sound heard coming

from the engine area on some 2019-2020 Blazer models

equipped with the 3.6L 6-cylinder engine (RPO LGX). The

sound may be more noticeable after driving the vehicle

for a while.

The sound may be caused by plastic flashing restricting

the clean air port on the air cleaner duct on top of the

engine.

It will appear that the restriction or flashing is partially

blocking the hole inside the air tube, about 2 inches

(5 cm) inside the tube.

To correct the condition, replace the air cleaner duct.

After installing the new air cleaner duct, run the engine

long enough to build up crankcase pressure and check for

any noise conditions.

Thanks to Aron Wilson

Clean air port

Restriction inside the air tube

October 2019 – Page 6

CONTINUED ON PAGE 7

NewEL-52545 TPMS RF Tool&MAKES TPMS SENSOR RELEARN EASY

System (TPMS) was federally mandated (U.S.) in 2008, radio

frequencies have been used on GM models to communicate with

the system and to determine the location of each TPMS sensor on

the vehicle. Today, there are three radio frequencies used in pro-

duction of GM vehicles.

The new EL-

52545 TPMS

and RF tool,

which will be

shipped as

an essential

tool to all

GM dealer-

ships in the

4th quarter

of 2019, fea-

tures a new communication protocol for TPM systems and Remote

Keyless Entry systems. It’s designed to take advantage of the new

Next Generation Digital Vehicle Platform electrical architecture

coming on the 2020 Corvette, CT5 and CT4 as well as future

models. It’s also backward compatible to 2008 and later GM mod-

els.

The EL-52545 TPMS and RF tool package includes:

• TPMS Module

• USB Cable

• RJ45 Cable

• Power Adapter

• OBD II Module

• Hand Strap

• Storage Case

The EL-52545 tool features a QR code reader to help identify the

make and model of a vehicle. It also uses an internal database to

determine the proper sensor transmit frequency for a vehicle.

ROTATE, DIAGNOSE, RELEARNA recent GM study of 2018 model year vehicle has shown that

TPM DTCs C0750, C0755, C0760, C0765 (Tire Pressure Sensor

Low Voltage, Too Few Pulses, and Internal Malfunction codes)

combined to account for more than 20% of all codes set, most

of which set after a maintenance event (tire rotation) or dealer

installation of accessory wheels. The EL-52545 tool changes

TPMS relearn communication from radio frequency to writing

IDs directly via the Diagnostic Link Connector (DLC), which is

expected to increase the success and quality of relearn proce-

dures to 100%, without any time penalty when doing a normal

tire rotation. As long as the tool is placed by the proper tire, an

incorrect sensor cannot be learned, which will greatly reduce the

common issue off learning a stray sensor on a near-by vehicle.

The Rotate–Diagnose–Relearn (RDR) function of the EL-52545 tool

can be used anytime the TPMS or tires are serviced on a vehicle,

such as a tire

rotation or

if the TPMS

warning

lamp is illu-

minated. All

TPMS data

is available

on the tool.

For example,

the tool will

highlight a

wrong frequency that is deployed in a wheel. And by connecting

via DLC, TPMS DTCs that are set can be identified with the TPM

IDs learned to the vehicle vs. what is present on the vehicle.

SENSOR RELEARNUsing the tool is easy. Here’s how to quickly relearn the TPMS

sensors after a tire rotation. The procedure is a simple process of

collecting the sensor data and then providing that data to the BCM.

Begin by selecting the RDR function using the tool controls. The

vehicle should have the ignition off or in service mode. The VIN

screen on

the tool will

prompt you

to scan the

vehicle’s QR

code, typi-

cally found

on the Tire

and Loading

Information

label, in order

to identify the

New EL-52545 TPMS and RF tool

Main menu

Use the tool’s QR code reader to identify the vehicle.

October 2019 – Page 7

vehicle. Aim the top of the tool at the code. The tool will beep

when it has read the code. If the vehicle does not have a QR code,

use the tool menu to select the vehicle by make, model and year.

Move to the

left front tire

and place

the front

edge of the

tool against

the tire at

the valve

stem. Press

the green

button on

the tool to

activate the sensor. The tool will beep once it has the data and

will display the sensor information. Repeat the procedure on the

right front tire, followed by the right rear tire and left rear tire.

With all four sensors activated, the screen will show the data

for each sensor. If the data shown is in white, the tool does not

see any frequency concerns with the sensors. Any concerns are

highlighted

in red. Direc-

tions for the

next step are

shown on

the screen.

Next, con-

nect the

OBD II mod-

ule cable to

the tool and

to the DLC in the vehicle. With the vehicle ignition on, engine off,

press the OK button and the tool will begin communicating with

the BCM and the screen will show a status update. The relearn is

complete if the screen displays “No additional action required.”

The RDR function ensures that the TPMS sensors are functioning

properly as the tool is able to evaluate IDs bolted to the vehicle vs.

BCM IDs and malfunction codes. The prescriptive repair direction

or clear indication messages (“No additional action required”) on

the screen provide concise information on system status as well as

next steps.

TOOL UPDATESThe EL-52545 tool software can be updated to ensure the lat-

est information is being used. As with other tools, the software

updates will be available through the gmtoolsandequipment.com

website.

Future software releases will add more functionality to the tool,

including a new Trailer TPMS feature that can be used to check

the Trailer

TPM System

available

on new Sil-

verado and

Sierra mod-

els.

In addition,

the EL-52545

tool has the

ability to ser-

vice non-GM

vehicles, sup-

porting the

dealership’s

used vehicle

department.

To see the

EL-52545

tool in the

service bay,

check out

the July 2019

edition of the

GM Service Know-How Emerging Issues seminar, 10219.07V, on

the GM Center of Learning website. In Canada, review the August

2019 TAC Talk program. The video covers four typical TPMS situ-

ations, including a normal sensor relearn after a tire rotation, a

vehicle with the wrong frequency sensor installed on one wheel,

a vehicle that learned a stray sensor on a close-by vehicle, and a

vehicle with a malfunctioning TPMS sensor.

Look for more details about the EL-52545 TPMS and RF tool

coming soon in TechLink, including a review of the radio fre-

quency functions of the tool.

For more information about the new EL-52545 TPMS and RF tool

package, visit gmtoolsandequipment.com.

Thanks to Bob Wittmann

Place the front edge of the tool against the tire at the valve stem to relearn the sensor.

When complete, the tool displays a “No additional action required” message.

ID information and repair direction is provided on the screen.

Data is shown for each sensor.

October 2019 – Page 8

CONTINUED ON PAGE 9

Currently being rolled out to select dealerships in the U.S.,

Techline Connect brings together all the common resources

technicians use every day for diagnosis and repairs in one simple

application. The all-new application has a single sign-on for access

to nine applications — integrating Service Information, repro-

gramming, diagnostics, vehicle information and other features

— to help technicians efficiently and accurately manage the

information available to them in the service department.

To help technicians get up and running quickly with Techline

Connect (TLC), here are a few tips about some of the key features

of the application.

TECHLINE CONNECT ICONOnce Techline Connect has been installed on the PC, a Techline

Connect icon will be placed on the desktop that will allow

direct access to the application without having to log in to

GlobalC onnect.

SELECT VCI DEVICEChoosing Select VCI Device at the top of the dashboard screen

will display any connected MDI tools (USB connection) or MDI

tools that are wirelessly connected and active.

Selecting an MDI tool will establish the MDI connection and

attempt to establish a vehicle connection, retrieving the VIN.

STARTING A SEARCHAlways start by clicking Select Vehicle at the top of the dashboard

screen. From here, you can:

• Enter a VIN by typing or copy and paste

• Select a Year/Make/Model

• Select a previous search from history

SEARCH SIAfter entering a VIN or selecting Year/Make/Model from the Select

Vehicle function, select the Service Information (SI) application at

the top of the dashboard to begin using the Service Information.

The VIN and year/make/model will be populated automatically.

GETTING READY FOR

Techline Connect dashboard

Select VCI Device

MDI connection to a vehicle

Techline Connect

October 2019 – Page 9

CONTINUED ON PAGE 10

Enter a keyword or phrase in the quick search field at the top of

the dashboard and Techline Connect automatically performs an SI

search for the connected vehicle.

If you’d like to perform another SI search not related to the

connected vehicle while still maintaining the connection on the

dashboard, select the Search Another Vehicle option under the SI

menu.

PANEL MANAGEMENT

The multi panel view function allows up to four panels to be

shown on the screen at one time, which can be helpful, for

example, when using GDS 2 while viewing diagnostic informa-

tion and a schematic in SI. Right-click on a link and select Open

in a New Page to open it in a new panel. Click and drag the top

of the panel to move its location or grab the border to resize the

window.

To enable the multi panel view function, go to the Profile section

under the User I.D. menu at the top right of the dashboard and

select the desired screen mode. If the maximum number of panels

are currently in use when opening a new panel or application,

Techline Connect will ask which panel to replace with the new

panel or app. Also, any panel can be selected to be viewed full

screen. Click the X at the top of each panel to close it.

SIGN OUT (STANDALONE)

The standalone sign out option under the Profile menu allows you

to log out of Techline Connect (no connection to the Service Infor-

mation and SPS) but still use GDS 2 diagnostics during a test drive.

Start by clicking Select Vehicle

Use the quick search field to perform an SI search.

Multi panel view

Select the number of panels in the Profile Preferences.

Select the Standalone option to use GDS 2 during test drives.

October 2019 – Page 10

CONTINUED ON PAGE 11

PRINTING To view the printing options, right-click in any panel to access

the print dialog box. The Service Information (SI) page will open

in the default browser to print. If viewing an image in SI, use the

Print button available in the image viewer. Plug-ins are no longer

needed when viewing SI using Techline Connect.

SCREEN RESOLUTIONChange the screen resolution based on the size of the monitor

being used to make it easier to view and use the apps. The resolu-

tion can be changed on the PC under the display settings. Right

click on the desktop to access the settings.

DTC CHECKUse the GDS 2 app to perform a vehicle-wide DTC scan from the

Techline Connect dashboard. This feature is only available to use

on vehicles with a global electrical architecture (Global A and Next

Generation Digital Vehicle Platform vehicles). Vehicles that use all

other protocols (GMLAN, Class II) require the Tech 2.

In order to use the GDS 2 DTC check, an active MDI/VCI and

vehicle connection is required.

The DTC check will report communication with vehicle control

modules and any DTCs detected.

• A green box indicates successful communication with the

module but no DTCs.

• A red box indicates successful communication with the module

and that DTCs were detected. Select each red box to view the

related DTCs.

• A grey box indicates no communication with the module, which

can mean that the module does not exist on the vehicle or that

the module is not responding.

CLEARING ALL DTCSAfter programming using the SPS application, go to the Techline

Connect dashboard and use GDS 2 to clear all DTCs vehicle-wide.

When using GDS 2, it clears all DTCs, while using SPS does not.

APPLICATION UPDATESThe new Update Manager that is part of Techline Connect will

perform all updates needed to keep the applications up to date

when logging in to Techline Connect, including GDS 2 and MDI

updates and large calibration files (if configured in the Profile

Preferences). To ensure all updates are downloaded properly, make

sure your dealership’s IT department correctly configures all of the

Techline PC’s security settings.

If the PC’s security settings do not allow updates to occur or be

seen by the user, Techline Connect will continue the log in pro-

cess. As a result, the app may not be up to date at all times. If a

core update for Techline Connect is not made, it will affect all of

the component apps.

TIP: Many dealership networks have elevated administrative

rights. If Techline Connect on your PC is not getting updates, try

to run as admin. Right-click the Techline Connect icon, and then

select Run as Administrator.

Updates for Techline Connect are typically released on weekends.

If an app works on Friday, but does not on Monday, it may be due

to the PC security settings not allowing the update.

Use the GDS 2 app to perform a vehicle-wide DTC scan

Download Settings preferences

Getting Ready for Techline Connect cont.

October 2019 – Page 11

CONTINUED ON PAGE 12

Check the Messages box at the top of the Techline Connect dashboard to see if

an update has been released and should have been downloaded. A message will

be sent out when all updates are released. If the download did not occur, it may

be necessary to contact your dealership’s IT department or the Techline Customer

Support Center.

MAIL ICONThe mail icon at the top of the Techline Connect dashboard can be used to send

an email to the Techline Customer Support Center (TCSC) with any questions

about an application. For troubleshooting-related questions, it’s recommended to

contact TCSC directly. For vehicle-related issues, contact the Technical Assistance

Center (TAC).

QUESTIONS?If you have any questions on Techline Connect, contact the Techline Customer

Support Center at 1-800-828-6860 (English) or 1-800-503-3222 (French).

Thanks to Mike WaszczenkoRun as Administrator function

Intermittent Shift to Park MessageThere may be an intermittent Shift to Park message displayed

on the Driver Information Center (DIC) when the vehicle has

been shifted to Park and the ignition has been turned to the

Off position on some 2016-2019 Malibu, Volt; 2017-2019

Acadia; 2018-2019 Traverse; and 2019 Blazer models. The

Shift to Park message may be the result of a build-up of ma-

terial on the contacts of the Park switch when it is activated

in the transmission control (shifter) assembly. The excessive

material may cause a higher than expected resistance in the

signal circuit to the Body Control Module (BCM), and not allow

the BCM to electronically see that the vehicle is in Park, even

though the vehicle transmission is in the Park position.

If this condition is present, the BCM will turn on the Shift to

Park message and not allow the ignition to turn off, leaving

the ignition in Accessory mode. To reduce the inrush of current

that causes the excessive build-up on the contacts, install an

in-line shifter wiring harness jumper between the shifter base

connector and the console harness connector.

Shift lever in Park

Shifter wiring harness jumper

October 2019 – Page 12

CLEAN THE ELECTRICAL CONTACTSWith the vehicle in Park and the ignition off, remove the

transmission control (shifter) lever knob and boot assembly.

Next, clean the Park Switch electrical contacts by depressing

the actuation rod fully and then releasing the rod. Use the flat

side of a trim stick or your thumb and allow the rod to “snap”

back to the full up position. Repeat the cleaning procedure 50

times. It’s critical to clean the electrical contacts to ensure a

proper repair.

After completing the cleaning procedure, start the vehicle and

verify that the Shift to Park message is not displayed on the

DIC. If the Shift to Park message is still displayed, replace the

transmission control (shifter) assembly. A newly design trans-

mission control assembly is now available.

INSTALL JUMPER HARNESSIf the Shift to Park message is not displayed, install the jumper

harness. Remove the front floor console trim plate and discon-

nect the body harness from the transmission control assembly.

TIP: To gain access to the shift control wiring connector, it will

be necessary to remove only the front floor console trim plate.

However, on some models, it may be necessary to remove

the front floor console trim plate and reposition the console

assembly

Install the in-line shifter wiring harness jumper between the

shifter base connector and the console harness connector.

The jumper harness should not be twisted or kinked in a 90

degree position.

Start the vehicle and verify that the Shift to Park message is

not displayed. Reinstall the front floor console trim plate and

any other trim panels as well as the transmission control lever

knob and boot assembly.

Refer to Bulletin #19-NA-206 for additional information and

part numbers.

Thanks to Tom Burlingame

Remove the transmission control lever knob and boot assembly.

Remove the front floor console trim plate.

Install the in-line Shifter Wire Harness JumperClean the Park Switch electrical contacts by depressing the actuation rod 50 times.

October 2019 – Page 13

GM TechLink is published for all GM retail technicians and service consultants to provide timely information to help increase know ledge about GM products and improve the performance of the service department.

Publisher: John Meade GM Customer Care and Aftersales

Editor: Lisa G. Scott GM Customer Care and Aftersales

Technical Editor: Mark Spencer mspencer@gpstrategies.com

Production Manager: Marie Meredith

Creative Design: 5by5 Design LLC dkelly@5by5dzign.com

Write to: TechLink PO Box 500, Troy, MI 48007-0500

GM TechLink on the Web: GM GlobalConnect

General Motors service tips are intended for use by professional technicians, not a “do-it-yourselfer.” T hey are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the information applies to your vehicle or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information. Inclusion in this publication is not necessarily an endorsement of the individual or the company.Copyright© 2019 General Motors. All rights reserved.

Some 2019 Silverado 1500, Sierra 1500; and 2020 Silverado

and Sierra models may have a discharged battery, the ignition

may not turn off, a Shift to Park message may display on the

Driver Information Center and the Check Engine light is illumi-

nated. There also may be a lack of communication with the K71

Transmission Control Module (TCM) and E20 Engine Control

Module (ECM) along with one or more of the following DTCs

set in the TCM: U007B, U0100, U0101, P0658, P0707, P2803,

P0712, P07BF, P0722, P077C, P0960, P0962, P0964, P0966,

P0968, P0970, P176C, P17CC, P2670, P2718, P2720, P2727,

P2729, P2736, P2738, P2812, P2814, P281B, P281D, P2824,

and/or P2826.

These con-

ditions may

be caused

by the TCM

connector

not being

seated and

latched

properly,

resulting

in poor

terminal

connection from the TCM to the engine harness. The TCM

connector is a multi-wire electrical connector, which can set a

variety of DTCs. Different conditions and driver notifications may

be caused by one of the terminals in the electrical connector not

coming into contact with the pins in the module. Components

on different lines are in different circuits. Due to the cause of

the condition, and the positions of the wires in the connector, it

is unlikely

that more

than one

circuit will

be affected

by the

condition.

Inspect the

K71 TCM

connector

for proper

seating. An

initial inspection may show that the

connector is cocked or high on one

side of the connector body.

One of the lever lugs on the TCM

connector may be coming out of

position on the horizontal sliding

lock bar, which may cause the drive

lug to slide along the outside of the

locking bar. Operating the lock lever

may show that the lock is not mov-

ing properly.

To correctly install the TCM connec-

tor, place the connector onto the

TCM and squeeze the connector

lever lock housing to ensure the lock bars are moving into the

proper position on the TCM connector body.

Thanks to Kevin Minor

Transmission Control Module Connector

Inspect TCM connector

Lever lug out of position

Lock bars in the proper position